EK system 2000 - internal plate heat exchanger leak?

Hey all, thanks for the forum!

The background: We have a System 2000 boiler which was installed in 2007. One problem I've been having with it because of our hard water is the plate heat exchanger clogging. I purchased an extra one, and have to swap every 8 months, and clean out the old one with Sizzle.

Recently I had to shut the residential water off, due to a shower valve behind the wall that corroded and sprung a leak. We had the water off for 3 days. On the third day, my wife called me in a panic - the boiler was making a loud grating noise, and before I could get home, started exhausting steam/hot water out the relief valve. Of course, I had her shut it off. When I turned it back on, it started loud sloshing, banging and the outgoing h20 temp went up to 270F! (I thought the system burner 2000 would shut off before going that high!)--anyway, i guessed the boiler was airlocked, so i purged and bled the whole thing. It worked fine after, and was quiet again. We had the same problem again after another day, and i realized there might be a leak (nothing visible anywhere that I could see though). Due to the fact that the residential was off, the make up water system was not supplying H20 and therefore the air lock. I fixed the shower valve and pressured the system, no more problem for about a week. Problem is back, and I suspected a leak in the exchanger, with boiler water escaping into our residential, therefore invisible. Maybe the numerous times i cleaned the exchanger with sizzle was too hard on it?

Has anybody ever heard of something like this, and the long range question would be, water softener or go indirect Hot water instead of plate exhanger? I'm done with cleaning them out every 8 months.

Thanks for any insight anyone may have,
Mike.

When there's a leak between the boiler water and potable water side of a heat exchanger the flow is usually from the potable into the heating system, not conversely. Potable water systems are usually run at 30psi or higher, which is the default pressure relief setting for many/most boiler's pressure relief valves. Most heating systems are set up to run at 12-15psi.

Slow leaks over the long term would cause the PRV to be spitting water frequently, and the heating system water pressure would be running way high. If you then turned off the potable water side and opened the valves the pressure on the potable side goes to zero, and the flow would go the other way.

Sizzle is primarily hydrochloric acid, which is WAY too aggressive to use on metal plumbing on a regular basis, and is very likely the cause of your leak.

I'm surprised that the System 2000 boiler was sold without an indirect, since it's claim-to-efficiency-fame is that it purges boiler heat into the indirect at the end of every call for heat(?). Yes, an indirect (set up to use the System 2K controls for optimal efficiency) AND water softener are both in order. (Indirects can lime up in hard water situations too.)

EK prefers to sell the system with PE and storage tank because it's more efficient than an indirect. During postpurge the entire tank becomes hot all the way to the bottom.

If you need to descale the PE a mild solution of Sizzle will not hurt it. You can also pump CLR or a similar descaler through it. Better yet, install a Cuno (AquaPure) Scale Stopper in the cold water feed. Replace the cartridge yearly and you will not have any further problems.

Running a boiler continuously to provide hot water is not particularly efficient. On many of the newer boilers, they can shut off entirely in between calls for heat, whether that is for space heating or DHW. Thus, an indirect may be a lot more efficient, and personally, convenient since you aren't flow restricted to maintain a decent volume of hot water, should you want more flow at any one time than the heat exchanger can provide.

The plate exchanger is always installed in conjunction with a storage tank sized to the hot water demand of the house. The boiler doesn't have to remain hot or run for every DHW use. Minimum recommended tank size is 40 gallons which is adequate for an average family. A larger tank would be installed if there is a large tub or Jacuzzi that may require 60-80 gallons or so for a fill.

The system 2000 is usuall sold with an indirect tank heated with a stainless steel plate exchanger. Sizzle won't touch the stainless steel exchanger so I'm guessing that your problem is with the limit aqua stat to sensing boiler temperature. It's the one located below the burner at the front of the boiler. Could be a manager problem also. They are complicated so having a trained service tech diagnose it is a good idea. Yes indeed, soften your water too.